Some physical and mechanical properties of African birch (Anogeissus leiocarpus) timber

The use of locally manufactured or waste materials in structural buildings without loss of performance is very crucial to the growth of developing countries. This report provides the results of some physical and mechanical property tests carried out on air dried African birch (Anogeissus leiocarpus) timber grown in Nigeria. Samples of the African birch timber were procured, naturally seasoned and their properties determined, in accordance with British Standard BS 373, for moisture content, specific gravity, and density while mechanical tests carried out are for tensile, compression and static bending. Strength values were obtained and further converted to 18% moisture contents (MC) which is the acceptable moisture content of timber to be used in Nigeria. The result of this experiment revealed that African birch timber possess a tensile strength of about 16% the strength of high yield steel and about 31% the strength of mild steel at 18% MC. Also, strength properties of African birch timber perpendicular to grain were found to be much lower than its strength properties parallel to grain.Keywords: African birch; Grain; Property; Strength; Timbe

Variation in the physico–mechanical properties of granitic aggregates in Ogun State, Nigeria

Coarse aggregate is an essential constituent of concrete constituting about 60% to 80% of concrete depending on the mix ratio. Granite is reported to be the most widely distributed plutonic rock in the earth crust. It is predominantly available in various parts of Ogun State of Nigeria. Its different properties have been known to strongly influence the fresh and hardened state properties of concrete. In this study, samples of four different sizes of granites (9.5mm, 12.5mm, 19mm and 25mm) were obtained from four different quarry sites across the state. The Physical properties such as specific gravity, moisture content and water absorption and the Mechanical properties such as aggregate impact value and aggregate crushing value of the samples were evaluated. The results of the specific gravity, moisture content and water absorption vary from 2.61 to 2.86, 0.69 to 1.22%, 0.16 to 2.13% respectively. While the aggregate impact value and aggregate crushing value vary from 18.30 to 28.12% and 6.21 to 9.45% respectively. It was therefore concluded that there are variations in the physical and mechanical properties of granites produced in Ogun State of Nigeria. The observed variations occur in relation to the various sizes and for the different quarry sites.Keywords: Variation, Physical Properties, Mechanical Properties, Granit

The Use of Lateritic Soils as a Cover Material in Municipal Solid Waste Landfills in Nigeria

Classification tests were undertaken on lateritic soils ( Soil A, Soil B, Soil C, Soil D) obtained from four borrow pits near the main waste dump being used for the disposal of municipal solid waste (MSW) produced by the residents of Ado Ekiti, Nigeria. Classification according to BS 5930 indicated the soils as clayey SAND (clay of intermediate plasticity). Using AASTHO classification system, Soil A and Soil C were classified as soil type A-2-6 and Soil B and Soil D were classified as soil type A-2-7. The effectiveness of different soil types used as cover material were rated and the different functions of the cover materials in a landfill were ranked according to their perceived importance. Overall rating of the performance of each soil as daily cover and as intermediate cover were obtained from the mathematical computation using the ranking and rating of each soil. The results show that the lateritic soils tested in this study are good as intermediate cover. Although the lateritic soils appear to be fair as a daily cover, it may be used if the clay content is excluded as much as possible. Keywords: daily cover, intermediate cover, lateritic soil, municipal solid waste landfill, rating, ranking

Re-evaluation of characterisation and classification of Apa (Afzelia bipindensis) timber for structural use

As a result of effect of geographical location on timber properties, there is need for constant determination of properties of timber. This paper presents the results of experimental tests carried out on three Apa (Afzelia bipindensis) timber logs grown in Kwara State, south-western periphery of the North Central Zone of Nigeria in order to ascertain its structural strength properties. Logs of Apa timber were air-dried and along the stem, 324 pieces of test specimens were prepared for determination of their strength properties using a universal testing machine (UTM) FS50AT model, (specimen prepared included 108 samples for tensile strengths parallel to grain, 108 samples for compression parallel to grain and 108 samples for bending parallel to grain) at a moisture content of 12%, in accordance with the Nigerian, British and European standards. The moisture content of 12 % was converted to 18% which is specified in a standard document, for the area. Statistical analysis was carried out using the strength properties for determination of mean, standard deviation, confidence limit and characteristic strength. The result revealed that the timber is satisfactory for structural purposes in construction works.Keywords: Apa, bending strength, classification, compressive strength, structural us

Characterisation and grading of three selected timber species grown in Kwara State Nigeria according to EN 338 (2009) for structural use

This paper is aimed at classifying three potential timbers grown in Nigeria using EN338 (2009) strength classification for structural size specimen. The timbers namely Vitex doniana, Ceiba pentandra and Pseudocedrela kotschyi were obtained in Ilorin, Kwara State of Nigeria. Physical and Mechanical properties of the selected timber species were determined in accordance with EN 13183-1 (2002) and EN 408 (2003) for structural timbers. Four point bending tests based on EN 408 (2003) with specimen 50x50x1000 mm were carried out using a Universal Testing Machine (UTM) to determine the bending strength and Modulus of Elasticity of the each timber specie. Characterisitc values of Bending strength, Modulus of Rupture and Density were determined using EN 384(2004). The timber species; Vitex doniana, Ceiba pentandra and Pseudocedrela kotschyi had equilibrium moisture content (EMC) of 15.70%, 13.71 % and 24.28 % respectively. Strength grading of timber species was then conducted by adjusting the material properties values of species to 12 % moisture content using the required adjustment factors. The timber were then graded according to EN338 (2009). Pseudocedrela kotschyi had the highest density of 813 kg/m3 followed by Vitex doniana (706 kg/m3) while Ceiba pentandra had the lowest density of 402 kg/m3. Vitex doniana, ceiba pentandra and Pseudocedrela kotschyi were assigned to strength class D30, C16 and D35 respectively in accordance with EN338(2004).Keywords: Bending strength, classification, density, modulus of elasticity, Nigerian grown timber structural us

Characterisation and grading of two selected timber species grown in Kwara State Nigeria

This study investigates the physical and mechanical properties of two timber species for structural use. Three logs of each specie were obtained at different areas of Kwara State, of Nigeria which is located north in the periphery of the south-western rain forest area, sliced into 2” by 12” size before seasoning naturally and their structural/strength properties were determined at a moisture content of 18%. These logs were cut into test samples for the determination of their properties. A total of 351 samples (45 samples for each test) free from visible defects was used for each specie. Basic physical properties of the samples like moisture content, specific gravity and density was determined. Tensile strength, modulus of rupture, modulus of elasticity, compression, shear and hardness were the mechanical tests carried out according to BS 373 (1957), CP112 (1971), NCP2 (1973), EC5 (1995) and BS 5268 (2002) specifications on Universal Testing Machine (UTM). Results were analysed statistically using Analysis of Variance (ANOVA). A. Indica was graded into strength class D40 while X. Aethiopica was grade into strength class D70.Keywords: Azadirachta indica, Characterisation, Grading, Mechanical properties, Physical properties, Structural timber, Xylopia aethiopic

Paraparesis in a patient with advanced HIV disease without manifestations of opportunistic infection

HIV infection had been associated with many symptoms and signs but the least expected is paraparesis in the absence of constitutional clinical  features. This case presentation is to highlight the unusual presentation of a 43 year old who presented with difficulty in walking due to gradual weakness in his lower limbs (more on right than left) and difficulty in passing urine of 8 months duration. All the common symptoms and signs associated with advanced HIV infection were absent. Urethroscopy and prostate biopsy were done and showed normal findings. Cranial computerised tomography (CT) scan finding was normal, but lumbo-sacral Magnetic Resonance Imaging (MRI) showed degenerative disease suggestive of immunosuppression. HIV screening (Unigold and ELISA) and HIV confirmatory tests were done that showed reactivity to HIV-1 antibody and CD4 count and plasma viral load results were 226 cells/ mm3 and 126,000 copies/ml respectively. The patient was commenced on antiretroviral therapy and paraparesis started resolving. Keywords: HIV infection, Constitutional symptoms, Urinary obstruction, Immunological  parameter

Feeder's load balancing using an expert system

Abstract: The electrical distribution system is to ensure that an adequate supply is available to meet the estimated load of the consumers in both the near and more distant future. This must of course, be done for minimum possible cost consistent wit satisfactory reliability and quality of the supply. In order to avoid excessive voltage drcop and minimize technical loss. it may be econonmical to install apparatus to batance or partially balance the loads. It is believed that the technology to achieve an automatic load balancing lends itself readily for the implementation of different types of algorithms for automatically reconfiguring a distribution network system for optimal performance

Evaluation of compressive strength characteristics of structural-sized Apa (Afzelia bipindensis) and Opon (Lannea schimperi) timber species columns found in Nigeria

The work centers on the compressive strength characteristics of Nigerian Apa (Afzelia bipindensis) and Opon (Lannea schimperi) timber species columns of nominal lengths 200, 400, 600 and 800mm and a nominal width and thickness of 50mm by 50mm. The data revealed that, Apa and Opon have an average density of 652.74 and 472.60kg/m3 respectively. The mean moisture content (MC) of both species were less than the fibre saturation point (FSP) recommended value of 25-30% and the average strength at yield of Apa and Opon are 35.65 and 14.00N/mm2. The derived continuous equations for design of Apa column and Opon column are σ = 47.882-0.009λ and σ =17.211-0.007λ respectively. The results of the reliability analysis show that Apa and Opon timber species have reliability index of 0.64 and 0.65 respectively for a service life of 50 years, assuming other serviceability conditions are met. This design procedure is distinct and more effective than the usual procedure of classifying compression members as short, intermediate and long using their slenderness ratios. The paper therefore recommends the adoption of these equations for the design of compression members from these timber species in Nigeria.Keywords: Apa, Compressive strength, Opon, Reliability, Structural-size